JP3103942B2 - Composite wire for electrogas arc welding for multi-layer welding and X groove joint welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite for electrogas arc welding for multi-layer welding and X-groove joint welding, which is excellent in low-temperature toughness, particularly excellent in COD characteristics and workability, for a weld metal or a heat-affected zone. It is about wires.

[0002]

2. Description of the Related Art At present, in electrogas arc welding, high-speed welding and low heat input are possible. Therefore, temper-type 60 kg / mm ² typified by mild steel to side plate vertical joints of oil tanks. It is also used for welding high-grade steel. However, in welding for the purpose of using in a low temperature state of −20 ° C. or less, in the conventional composite wire for electrogas arc welding, the toughness of the weld metal itself and the reheated portion of the heat-affected zone cannot be secured, and The workability is poor and it is not applicable despite the excellent welding efficiency. For this reason, it has been considered difficult to apply such as a multi-layer pile at low temperature or an X groove joint.

As means for improving the toughness of a weld metal in electrogas arc welding, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent No. 48495, a method of using a wire in which Mo, Ti, and B are added to a slag agent essentially containing CaF ₂ and NaF in a flux surrounded by a steel sheath has been proposed. It is not an effective measure.

[0004]

SUMMARY OF THE INVENTION The present invention aims at improving the low-temperature toughness of the weld metal and the reheated portion of the heat-affected zone, improving slag fluidity, and improving workability. By suppressing the coarsening of the crystal structure against reheating, the low-temperature toughness of the reheated portion of the weld metal and the heat-affected zone is improved,
In addition, the present invention provides a composite wire for electrogas arc welding for multi-layer welding and X-groove joint welding, which can improve the fluidity of slag, improve workability, eliminate the drawbacks of conventional wires, and expand the field of application. Things.

[0005]

The gist of the present invention is as follows. (1) The slag forming agent is composed of metal fluoride and metal oxide, and the weight ratio of metal fluoride / metal oxide = 0.3 to 0.8.
Is filled into a steel sheath, and a slag forming agent: 0.7 to 1.5%, Mn: 0.7 to 1.5%, Si: 0.15 to the total weight of the composite wire. 0.5%, Mg: 0.1 to 0.6%, Ti: 0.05 to 0.25%, Ni: 1.5 to 4.5%, B: 0.002 to 0.02%, iron Flour: 10 to 25% in flux, Crust in skin + flux
Sum from 0.02 to 0.06% der in it is, and substantially the Mo
Multi-layer assemblage and X pioneer successor not characterized
Composite wire for electrogas arc welding for manual welding .

(2) In the composite wire as described in the item 1, the total weight of the composite wire in the filling flux is A
and a multi-layer asperity containing 0.005 to 0.25%
Composite wire for electrogas arc welding for X groove joint welding .

[0007]

The present inventor has been involved in the research of electrogas arc welding for many years, and as a result of repeatedly conducting trial production of wires for many years, as a result, it has been found that the weld metal of the multi-layer pile and the X groove joint and the reheated portion of the heat-affected zone. In order to improve the low-temperature toughness, improve the fluidity of the slag, and improve the workability, Mo present in the weld metal has the effect of coarsening the microstructure during reheating. Addition of Ni, which makes the microstructure finer and uniform without heating, does not cause coarsening. Also, if the amount of oxygen in the weld metal is excessively increased, the microstructure becomes coarse and becomes a source of oxygen. Is the metal oxide of the slag forming agent, but without the metal oxide, the fluidity of the slag deteriorates and the workability deteriorates. By ratio 3 points that focus the finding that it is effective obtained.

[0008] Therefore, by combining the knowledge of the three points, Ni is added to the filling flux except for the conventionally added Mo, the slag forming agents are metal fluorides and metal oxides, and the mixing ratio is adjusted to a certain range. When the experiment was repeated, it was possible to obtain a composite wire having excellent low-temperature toughness of the reheated portion of the weld metal and the heat-affected zone, which was not found in the conventional wire, and also excellent workability. Reached.

Hereinafter, the component composition of the filling flux will be described. The slag agent melts under the arc temperature and not only covers the molten pool surface as liquid slag, but also solidifies later than the molten metal, and exhibits a low viscosity in these processes to protect the semi-solid film on the beet surface. . Therefore, it is necessary to lower the melting point of the slag to some extent, and for that purpose, the metal fluoride should be blended in a ratio of 0.3 or more to the metal oxide. That is, if it is less than 0.3, the melting point of the slag is high and the viscosity of the molten slag is large, so that there is no effect. Further, the oxygen content in the weld metal increases, the microstructure becomes coarse, and the low-temperature toughness of the weld metal and the heat-affected zone is poor. On the other hand, if it exceeds 0.8, the viscosity becomes too low, and the slag itself becomes scattered or jumps, and the arc also becomes unstable rapidly.

[0010] When the slag forming agent is less than 0.7%, the slag encapsulating property is poor and the bead shape is deteriorated. 1.5%
In the super, the microstructure becomes coarse and the arc becomes unstable,
Excessive slag causes defects such as undercut. Therefore, the upper limit was set to 1.5% and the lower limit was set to 0.7%. Na ₂ O, K ₂ O, Si
O ₂ , TiO ₂ , Al ₂ O ₃ , CaO, MgO, ZrO
₂ , oxides such as MnO ₂ , NaF, KF, CaF ₂ , M
A non-metallic powder of a fluoride such as gF ₂ or BaF ₂ is added in the form of a simple substance or a compound.

The sum of C in the outer skin and the flux is 0.02
The reason for limiting to 0.06% is as follows. The Si, Ti and Al elements used for the purpose of degassing and remaining in the weld metal facilitate the abnormal growth of ferrite. C is added to prevent this. If less than 0.02% of C is added, the effect of preventing the abnormal growth of ferrite cannot be obtained. In addition, droplet transferability is deteriorated. If it exceeds 0.06%, the strength of the weld metal increases and hot cracking occurs. C from the filled slacks is contained in the form of graphite alone, in the form of an alloy such as Fe-Mn-C, or in the form of carbonate. C added from the outer shell is contained in the steel outer shell in the form of an alloy.

Mn is added to adjust the fluidity of the slag, improve the beat shape, promote the deoxidation of the weld metal, and provide suitable strength to the welded joint. 0.7%
If it is less than the required strength, the required strength cannot be obtained. On the other hand, if it exceeds 1.5%, the strength is improved but the toughness is deteriorated. Therefore, the addition amount of Mn is set to 0.7 to 1.5%. Note that M
n is used alone, and Fe-Mn, Fe-Si-M
It can also be used in the form of an iron alloy such as n.

[0013] Si is an effective deoxidizing agent and improves beet appearance and welding workability. However, if it is less than 0.15%, these effects cannot be obtained. However, if it exceeds 0.5%, Si in the weld metal becomes excessive and deteriorates toughness, which is not preferable. Therefore, Si is 0.15 to 0.5
%. Note that Si is a simple substance or Fe-Si, Fe
It can also be used in the form of an iron alloy such as -Si-Mn.

[0014] Mg is a strong deoxidizer. Particularly, it is optimal for reducing the amount of oxygen in the weld metal. 0.1
%, The effect cannot be sufficiently obtained. On the other hand, if it exceeds 0.6%, the welding workability deteriorates, the amount of spatters generated increases, and the low-temperature toughness also deteriorates. Therefore, the appropriate range of Mg is set to 0.1 to 0.6%. Mg is simple substance or Ni
-Mg, Ca-Mg, Fe-Mg, and Fe-Si-Mg may be added in the form of an Mg alloy.

[0015] Ti forms a Ti oxide, refines the microstructure of the weld metal, and is effective for improving low-temperature toughness.
Since the effect cannot be expected if the content is less than 0.05%, the lower limit is set to 0.05%. If it exceeds 0.25%, the low-temperature toughness is significantly impaired, so the upper limit is made 0.25%. Ti may be added as an alloy such as Fe-Ti in addition to metal Ti.

[0016] Since B is a strong deacidified carbide forming element, by adding it to the wire, the crystal grains in the weld metal are refined. In addition, there is an effect of enhancing the hardenability of the weld metal, and in order to obtain such an effect, a minimum amount of 0.002% of B is required. Since high temperature cracks are likely to occur, the upper limit is made 0.02%. Fe as B source
-B, atomized B or the like can also be added.

Ni is effective in increasing the toughness of the weld metal. In particular, Ni has the advantage that the toughness does not decrease even when reheated. However, if it is less than 1.5%, it is ineffective, and if it is more than 4.5%, it is ineffective. If there is, high temperature cracking of the weld metal will occur.
5%, and the upper limit is 4.5%. In addition to the above, Al can be added to the wire of the present invention. The addition of Al
It has the effect of promoting the effects of i and B, but 0.005
If it is less than 0.2%, there is no effect. Conversely, if it exceeds 0.25%, the weld metal becomes brittle and the toughness is reduced. Therefore, the lower limit is set to 0.0
05% and the upper limit is 0.25%. In addition, as a method of adding Al, it can be added in the form of a simple substance or an alloy such as Al-Mg or Fe-Al.

The filling rate of the flux is not particularly limited.
A range of 30% is most suitable. In addition, there is no limitation on the cross-sectional shape of the wire. In the case of a small diameter of 2 mmφ or less, a relatively simple cylindrical shape is used, and 2.4 to 3.2 mm
In the case of a large diameter wire of about φ, a wire having a structure in which a sheath material is complicatedly folded inside is generally used. In the case of a seamless wire, it is also effective to apply a plating treatment such as Cu to the surface.

[0019]

EXAMPLES Tables 2 and 3 were prepared using the skins of the components shown in Table 1.
Welding was performed using a wire prototyped with the flux composition shown in (continuation of Table 2). The results are shown in Tables 4 and 5 (continuation of Table 4). In Tables 2 to 5, the wire N
o. Nos. 1 to 5 are comparative examples; 6 to 15 are embodiments of the wire according to the present invention. 0.8mm thick, 1 width
A 1.1 mm mild steel hoop is filled with flux while being rolled, and a 1.6 mm diameter wire is used as a wire and welded under the following conditions. Tensile properties, impact properties, COD properties, X When the linear performance was examined, the results shown in Tables 4 and 5 were obtained.

Welding conditions Welding current: 380 A Welding voltage: 39 V Welding speed: 10 cm / min Shielding gas: CO ₂ , 35 l / min Groove shape: X-shaped joint (see FIG. 1) Base material: plate thickness 40 mm Material low-temperature steel SLA410 (JIS standard) Lamination method: single-sided, single pass The characteristics of the weld metal were adjusted using test pieces taken out from the center in the plate thickness direction and the groove width direction.

As is clear from the test results in Tables 4 and 5, it was confirmed that the wires outside the present invention had low low-temperature toughness, low COD value, and poor workability and X-ray performance. On the other hand, the wire according to the embodiment of the present invention has low temperature toughness, COD
It was confirmed that the value, workability and X-ray performance were good.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

As described above, the present invention removes Mo from the conventional flux, adds Ni, and further adds metal fluoride and metal oxide as slag forming agents in a certain ratio. Low temperature toughness of weld metal and heat affected zone, C
The OD value and workability were improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a groove of a welded joint used in an embodiment of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Kyo 5-10-1 Fuchinobe, Sagamihara City, Kanagawa Prefecture Nippon Steel Corporation 2nd Technical Research Institute (56) References JP-A-59-189097 (JP, A JP-A-58-9796 (JP, A) JP-A-4-89196 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/368

Claims (2)

(57) [Claims] 1. A slag forming agent comprising a metal fluoride and a metal oxide, wherein the weight ratio of metal fluoride / metal oxide = 0.3 to
A flux of 0.8 is filled in a steel sheath, and slag forming agent: 0.7 to 1.5%, Mn: 0.7 to 1.5%, Si: 0 based on the total weight of the composite wire. .15 to 0.5%, Mg: 0.1 to 0.6%, Ti: 0.05 to 0.25%, Ni: 1.5 to 4.5%, B: 0.002 to 0.02 %, Iron powder: 10 to 25% in the flux
Sum from 0.02 to 0.06% der in it is, and substantially the Mo
Multi-layer assemblage and X pioneer successor not characterized
Composite wire for electrogas arc welding for manual welding . 2. The composite wire according to claim 1, wherein the filling flux contains 0.005 to 0.25% of Al with respect to the total weight of the composite wire and the X-opening.
Composite wire for electrogas arc welding for tip joint welding .